CHAPTER 1 PROTECTION FROM TSUNAMIS

摘要

Artificial structures can be constructed to protect coastal areas from natural hazards, such as storm surges and tsunamis. However, they can cause environmental problems and are expensive. Recently, mangroves and other types of coastal forests and vegetation have increasingly been reconsidered as possible alternatives to be used instead of, or in conjunction with, artificial structures. Mangrove forests are vegetated inter-tidal wetlands that provide goods and environmental services, including protection against wave impact and erosion. The dynamics of tidal flow and wind waves moving through vegetation, including mangroves, are well understood. Tsunamis, on the other hand, are transient waves with much longer wavelengths, such that tidal research cannot be readily applied. Yet, quantitative evaluations of mangroves and other coastal forests as protection against a tsunami's potentially catastrophic impact are limited. This paper describes the effectiveness of forests in mitigating tsunami waves through hydraulic resistance (drag and impact force) owing to bottom roughness and vegetation. Numerical models to simulate the effectiveness of mangroves in reducing tsunami incursion are presented.